1. Technical Field
This invention relates generally to linear motion assemblies, and more particularly to ball screw assemblies.
2. Related Art
Ball screw assemblies are well known for use to effect linear actuation in various industries, such as machine tool, automotive, aircraft and aerospace, for example. Typically, a commercial ball screw assembly includes a screw with a continuous external helical ball groove and a ball nut with a continuous internal helical ball groove, with the external and internal ball grooves being configured with substantially identical uninterrupted leads to provide a single, continuous ball track. With the ball nut received on the ball screw and with the ball grooves arranged opposite one another, a plurality of balls are disposed in the single, continuous ball track between the opposed, continuously cooperating helical grooves. Typically, one or more ball return mechanisms are incorporated in the ball nut to re-circulate the balls over 1 or more turns of the ball track, wherein a single turn represents a 360 degree traversal about the circumference of the ball track. As the balls are re-circulated through their respective ball track, side surfaces of the mating helical grooves contact the balls under a compression load to counteract axial loads along a centerline of the assembly. Thus, while being well adapted to accommodate axial loading, the typical ball screw assembly is not well suited to support a radial load, also referred to as side loading or moment loading, in combination with an axial load imparted on the ball nut. As such, side loads typically have a deleterious effect on the load carrying capacity and useful life of the ball screw assembly.